The optimization of exergoenvironmental factors in the combined gas turbine cycle and carbon dioxide cascade to generate power in LNG tanker ship

Abstract

This study aimed to determine an optimum condition of a propulsion system in liquefied natural gas with a combined gas turbine cycle and carbon dioxide cascade serving as an eco-friendly alternative system due to its good performance. Moreover, Combined Gas Turbine Electric and Steam LM2500 25 MW propulsion system usually implemented in the HZ LNG Carrier ship was used as a case study. The analyses conducted were in two parts, and they include exergy analysis using Engineering Equation Solver and exergo-environmental, as a form of environmental effect analysis, using SimaPro. From these two analyses, the optimum condition was determined using the genetic algorithm method through the application of MATLAB. From the calculation, the exergy efficiency was found to reach 59% with a thermal efficiency of 43.76% while exergo-environmental was 38.15%. From this result, the optimization of the multi-objective was conducted using the Technique for Order of Preference by Similarity to Ideal Solution method and an increase in exergy efficiency to 60.93% was observed with a thermal efficiency of 46.78% while the exergo-environmental percentage decreased to 29.98%.